Sundial - what you are looking with those numbers are essentially two different types of workouts. One is more intense and shorter, the other is less intense and longer. Both have benefits and should be part of a comprehensive plan. Is one better than the other? That depends on your goals.

For most people, the best results come from variety - so both would be better than one or the other. Yay, more excuse to ride!

By the way, there are volumes written on the most effective form of cardio for weight loss, calorie burning, CV improvement, etc. Even the experts don't agree. Honestly, the best answer is that the BEST workout is the one you will do most consistently.